Comment 7 for bug 1585534

Also there are some problems in src/mcs/mir/screencast.cpp.
Here is the patch.
First of all, "output_.refresh_rate" is populated only for the whole output_ to be populated later, so I moved it at the end of the function.
Second, instead of the screen to be of the dimensions retrieved from the output, it is made from the dimession of the pone screen. It just so happend that my dongle has the same resolution with my phone screen so it worked, but here is the other half of the solution.